Cell invasion through basement membranes is crucial for both normal development and cancer metastasis but relatively little is known about the process because it is difficult to observe in vivo. By imaging the invasion of anchor cells during C. elegans development, Hagedorn et al. reveal that, after invadopodia-like structures form an initial breach in the basement membrane, localized netrin signaling helps generate a stable invasive protrusion that widens the gap and directs the cell across...